The manufacturing of integrated circuits (ICs) requires a number of discrete process steps to create packaged, semiconductor devices from a wafer. Under an normal circumstance, the wafer would go through all necessary steps step-by-step by following a preset process flow. That is, contents of each step, process parameters, and time sequences of the process flow would be preset, and the wafer would sequentially go through each of the steps.
A manufacturing of bullet lots may be a common phenomena in the IC manufacturing. One type of the bullet lots may be new type out (NTO) lots. That is, a smaller number of devices may be fabricated before customers use a FAB (semiconductor fabrication plant) for a mass production. Whether or not to order a large quantity of devices will be determined by the quality and turn out time of the bullet lots. Thus, NTO lots may bring the FAB a large number of subsequent orders, and may significantly improve the manufacturing capacity and performance of the FAB.
Further, abnormal lots may be found from a certain process step of a normal fabrication process. When the abnormal issue is found and solved, bullet lots may be urgently needed to test the feasibility of the solutions. If the solutions work well, they may be spread all over the FAB, thus the manufacturing of the bullet lots may contribute to the yield and productivity of the FAB.
Further, a new technology may be invented by engineers; the new technology may improve the manufacturing level of the FAB; and more customer orders may be attracted to the FAB. Thus, bullet lots of the new technology may need to be dispatched as soon as possible. Therefore, the bullet lot dispatch may significantly affect the yield, manufacturing capacity, and the process level of the FAB, it may need to be handled with a priority.
However, sources of the FAB have their limitation, how to reasonably allocate the sources to bullet lots without disturbing a normal manufacturing process may be a complex question. FIG. 1 illustrates a work flow of an existing bullet lot dispatch method.
As shown in FIG. 1, at the beginning of the bullet lot dispatch process, an online personnel may check if there are bullet lots in a load port need to be run (S101). If there are bullet lots need to be run, it may start to run the bullet lots (S102). If there is no bullet lot to be run, it may check if there are incoming bullet lots (S103). If there are incoming bullet lots, a standby load port may wait for the incoming bullet lots (S104). If there is no incoming bullet lot, the standby load port may run other lots (S105).
However, such bullet lot management and dispatch method may be cursory; and may be unable to match the requirements to optimize the manufacturing capacity of a FAB. The disclosed methods and systems overcome such problems set forth above and other problems by using a real time dispatch (RTD) system.